All other things being equal, being an expert is obviously preferable. However, many very smart people are also somewhat anti-social, and teaching is first and foremost a social event.
I have no fondness for schools of education or current teacher training, but you do not need a lot of expertise in individual subject areas to be a good teacher. You DO need to be good at working with others, and particularly at working with children. That skill, plus an average intelligence and reasonable lesson preparation, will result in kids learning. Without it, you can be a genius and not teach squat-all.
Another strawman argument!
Walter Williams never said that ONLY very smart people should teach. How can anyone defend a position of your own creation?
If you are a teacher, I hope you are not using this highly manipulative, and highly flawed debating technique with your students. I personally would consider this to be emotionally abusive to do this to emotionally and intellectually immature student who are held captive in your class by force of law.
Williams DID suggest that schools of education be eliminated. This would mean that students would need to declare another major. That would make them at least at smart as the other students graduating from these majors!
Such a person will be able to handle the difficult kids in her class, probably better than a rocket scientist. But what about the smartest kids? What happens when a bright third grader asks a question because he’s understood how the math works and wants to know more, but the teacher - because it’s not on the lesson plan - can’t help him?
The whole system is broken and one big reason why is that we have this idiotic notion of sticking thirty kids in a classroom with nothing in common except their age. That’s really easy to manage. What’s hard is if you have ten classrooms all teaching math at slightly different levels, and assign the kids based on their abilities. But if you did that there might be some learning.